SAN ANTONIO ? Michael Finley, Nick Van Exel, Steve Nash and the Dallas Mavericks wouldn’t let San Antonio clinch a spot in the NBA Finals.

Given the way the Spurs played in the fourth quarter, they didn’t deserve one.

On a night that shaped up as the final night of basketball until the championship round begins June 4, things didn’t work out that way at all.

The Mavericks fell behind by 19 points but never quit, staging a comeback throughout the second half that culminated in a stunning turn of events in the fourth quarter as Dallas defeated San Antonio, 103-91, Tuesday night.

“I saw blue shirts on the floor, I saw blue shirts ripping rebounds from guys in white shirts. They wanted it more and they deserved it,” Spurs coach Gregg Popovich said.

The Mavericks cut San Antonio’s lead to 3-2 in the best-of-seven series, with Game 6 Thursday night in Dallas.

Finley scored 31 points and got huge help in the fourth quarter from Van Exel and Nash — the two starting point guards in the small-ball lineup coach Don Nelson was forced to use as Dirk Nowitzki (knee injury) sat out his second straight game.

The Mavericks used a 14-2 run to take a 101-88 lead with 1:42 left, prompting San Antonio to call a timeout and Bruce Bowen to yell “Shut up!” three times at a heckler sitting behind the bench who was telling the Spurs how terrible they were.

The heckler was right.

Dallas outscored San Antonio 29-10 in the fourth quarter as the Spurs missed their first eight shots, 11 of 12 and 14 of 17 overall.

Dallas guard steve Nash, left, works the ball past San Antonio's Tony Parker. The Mavericks defeated the Spurs, 103-91, Tuesday night in San Antonio to force a sixth game in the Western Conference finals.

Dallas went 23-for-23 at the foul line overall and shot 56 percent from the field in the second half. Tim Duncan of the Spurs missed seven of 12 free throws by himself.

Blown fourth-quarter leads are nothing new to the Spurs this postseason, but this one was especially galling because the team that seemed to want it more was not the team that was one victory away from the finals.

“The goal is still to get to four, and we’re up 3-2. The goal is still to get to four before them,” Duncan said.

A steal by Finley and a fadeaway 12-footer by Nash made it 92-86, and Van Exel hit two from the line and then stole Malik Rose’s ensuing inbounds pass. He was fouled on a three-point shot and made all three, making it 97-86 with 2:32 remaining.

It was no contest the rest of the way as Dallas avoided its first four-game losing streak in more than three years.

Van Exel finished with 21 points, Nash had 14 and Walt Williams 12.

Duncan had 23 points and 15 rebounds for the Spurs, shooting just 1-for-2 from the field in the fourth.

Van Exel scored 12 points in the fourth and Nash had seven, with Finley adding four points and two steals.

Both Bowen and Rose finished the first quarter 3-for-3 as the Spurs shot 65 percent, didn’t commit a turnover and led 30-23. A 16-3 run ending with a 3-pointer by Stephen Jackson gave the Spurs their largest lead, 48-29.

Nelson slowed the game down the same way he did in Game 1 by intentionally fouling Bowen three times, but Bowen made four of his six free throws. If the strategy was intended solely to take the Spurs out of their flow, it worked.

Dallas' Raef LaFrentz dunks against San Antonio. The Mavs won, 103-91.

But Dallas was only able to climb back within 11 by halftime as the Spurs were still shooting 61 percent from the field.

San Antonio rebuilt its lead back to 17 with 7:47 left in the third, but the Mavs wouldn’t quit. Finley came out of a timeout and stole a sideline inbounds pass by David Robinson, turning it into two free throws to make it 70-59 with 5:48 left, and a drive by Van Exel made it a 10-point game.

Raef LaFrentz picked up his fifth foul defending Duncan with 5:01 left in the third, yet Nelson left him in a while longer and he never fouled out.

Finley continued to hit tough shots and create opportunities for his teammates, and the Mavs pulled within six late in the third before San Antonio took an 81-74 lead into the fourth.

Williams, Nash and Van Exel made the first three shots of the fourth quarter to pull the Mavs to 81-80, and a three-pointer by Nash completed the comeback and tied it at 83 with 8:35 left.

A dunk by LaFrentz off a pass from Nash gave Dallas its first lead, 85-84 with 7:30 left, and Van Exel’s driving layup upped the lead to three as the Mavs were on their way.

Notes: Dallas improved to 7-2 in the past three years when facing elimination. … Popovich spoke on the phone with departed Philadelphia coach Larry Brown. “I’m thrilled for him. I think he’s been in agony professionally and personally, and he’s back in control of his own life. I think he has a clear head.” Popovich refused to elaborate on his use of the word “agony.”